As entertaining as the Jurassic Park films and novels have been, the popular franchise has deeply distorted the public imagination of dinosaurs, and especially raptors. Compared to the movie version, real velociraptors were a great deal smaller, a lot less clever, and covered in feathers. Not all that different from many of today’s raptors. Yes, raptors still exist. Birds are dinosaurs, and in ornithology, “raptor” refers to birds of prey with strong grasping feet and wicked curved talons. We need only look at the claws of an eagle to see that these birds are very much raptors, and watching them hunt or clash gives us the closest glimpse we can see in nature of what the primordial world looked like when dinosaurs ruled the Earth. But that’s not the only thing the observation of eagles and other raptors shows. It turns out that in their mating and nesting habits, these modern-day dinosaurs can spread their bisexual wings as well as other birds.
In the early 2000s, researchers spent more than a thousand hours over a four-year period observing three Spanish imperial eagles in the wild. The birds had formed a polyandrous breeding trio with two males and one female. Together, the threesome successfully hatched and reared multiple chicks, which was atypical, as eagles usually form long-term bonds with a single partner. But this wasn’t just a peculiar cooperative parenting arrangement: three out of the four mountings observed were between the two males, the other being between one of the males and the female. In the 1980s, a pair of male Steller’s sea eagles in a Berlin aviary formed a bond so close that they were able to raise chicks from eggs the staff gave them out of curiosity, and refused female mates once they’d formed their bond.
More recently, a female pair of Bonelli’s eagles in Spain adopted and successfully fostered and fledged three chicks between 2024–2025. Similarly, in 2019, a trio of bald eagles with two males and a female raised multiple chicks. As a piece from the Audubon Society noted,
Even after their first mate died, the two males remained faithful to each other, and are now raising three eaglets with a new female.
Examples of bald eagle trios engaging in cooperative nesting have also been observed in Alaska in 1977, in Minnesota in 1983, and in California in 1992.
Same-sex behavior has been documented among other raptors as well, including bearded vultures, cape vultures, kestrels, and barn owls. Researchers studying two polyandrous trios of bearded vultures observed 167 total copulation attempts. From 1991–1992, over 26% of matings in the first trio were between two males. Observing a second trio from 2000–2001, they found that over 11% of the mountings were also male-male. They concluded that this bisexual behavior regulated aggression between the males. In 2020, a pair of female American kestrels in Texas had what researchers dubbed a “fling”, mating 23 times in a single day. Over a five-week period, the birds engaged in aerial courtship displays and copulated with one another an average of 9.2 times per hour, alternating who was “on top.” The study authors believe female-female pairings were helpful for stimulating ovulation and producing offspring whenever one female mated with a male, rather than having two mothers.
What’s most remarkable about raptor bisexual behavior is that we have any evidence at all, given that eagles and other birds of prey are among the most difficult animals to study in the wild. As the United States Geological Survey has noted, raptors occur in fewer numbers compared to other birds, are “wide-ranging”, “secretive”, and “dispersed” for much of the year. They can also nest in wildly hard-to-reach places, making them both “difficult to observe” and “very time-consuming and expensive” to study. Wildlife field research of these birds is also tightly regulated by governments, especially for eagles, as many species are endangered. If that weren’t enough, researchers have found that the very act of studying raptors can change how they behave: they know when people are around and “human presence can disturb eagle nesting and foraging.”
But, as with a great many other animal species, bisexual behavior is so widespread that it doesn’t require all that much observation to see same-sex behavior take place. There’s just no keeping a bi bird down.